function Get-Keyword(){
	$keyword = help about_language_keywords | Select-String -Pattern "^\s+(\w+)(?=\s+about_)" | Select-Object  @{n='keyword'; e={$_.matches}}       
	for ($index=0;$index -lt ($keyword).Count; $index++){
		Write-Host -NoNewline ("{0,-15}" -f ($keyword)[$index].keyword.value)
		if(($index+1) % 5 -eq 0) {Write-Host ""}
	}
}

function Pip-Install([string]$module) {
    $douban = "python -m pip install {0} -i http://pypi.douban.com/simple --trusted-host pypi.douban.com "
    $cmd = $douban -f $module
    Write-Output  "Invoke-Expression(`"$cmd`")"
    Invoke-Expression($cmd)
}